Causes
In most instances the cause of hives is never discovered and this is called Idiopathic Urticaria in medical terms. However the two causes of hives include: –
a. Immunological cause - Hives caused by changes in the immune system. It is essentially an acute antigen-antibody reaction that causes release of histamine from mast cells that are present in the circulating blood cells of the body.
b. Non-immunological – Here too it is the histamine that is released without the antigen-antibody reaction and can be caused by exposure of certain chemicals.
The most common triggering factors that cause hives include:-
- Medication such as antibiotics e.g. - penicillin or sulfa, codeine, anticonvulsant drugs, Phenobarbital, aspirin and many more
- Foods (nuts, berries, shellfish, prawns, tomatoes, jelly fish eggs, soy, eggs, milk, fish, chocolate)
- Food additives
- Pollen
- Animal dander
- Plants
- Insect bites (bee / wasp stings)
- Parasitic worms/infections
- Jewellery
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- Irritation from tight clothes
- Excessive sweating
- Extreme temperature
- Sunlight
- Exercise
- Viral/bacterial/fungal infections (Hepatitis-B common example)
- Emotional stress
- Autoimmune Diseases such as lupus
- Illnesses such as leukemia
 Sometimes the cause of hives cannot be determined.
